Energy efficiency is a serious consideration in building design and construction. Many building codes require builders to minimise energy requirements to maintain comfortable living spaces.
One of the most common energy loss in a building is due to the heat transfer through the attic. In some climates, heat builds up in the attic from solar energy incident on the roof or from heat transfer from the living space. If the attic is allowed to become too warm, the installed insulation becomes ineffective and the attic heat is transferred to the living space below. In colder climates, moisture builds up in the attic, sometimes significantly decreasing the efficiency of the insulation. Regardless of its numerous origins, moisture, if left unchecked, will build up and potentially cause extensive damage within the structure. Moisture originating from the shower, kitchen steam or the like not only potentially decreases the insulating value of the insulating material but also potentially leads to growth of mildew and mould.
Hence, it is relatively well known in the home building industry that proper circulation of air within the attic zone and above the level at which the insulation is installed is essential to avoid moisture build up during cold winter months and to maintain the un-insulated attic space at a reasonably low temperature during warm summer months.
Early efforts at minimising energy losses through the attic focused on the insulation between the living space and the attic have ignored the effects of the heat and/or moisture build-up. As insulation improved, a point was reached where more insulation was not necessarily better or possible due to space limitations. Numerous attempts have been made to alleviate this problem by installing vents at various points in the roofing structure. One common technique is to include vents or venting apertures on the underside of the soffite of the roof as, for example, on the underside of the eaves. While this practice allows some of the heat to escape, the ventilation provided remains poor. Indeed, because the vents are located on the underside of the eaves, the heat must build up to relatively high levels before it is forced downwardly out of the vents due to the fact that the heat naturally rises. This also causes a non-uniform heat distribution within the attic or roof's structure.
Since the heat rises, the temperature closest to the roof will constantly remain at temperatures higher than that of the areas further away from the roof and near the eaves. Also, in sloped roof structures, the heat will concentrate adjacent the apex, creating higher temperatures of the apex which steadily decrease along the roof line towards the eaves. Hence, the air allowed to escape of the eaves is not even the hottest air.
In order to increase ventilation, turbine-type roof ventilators are sometimes used. These turbine roof ventilators typically include a sleeve on the top of which is mounted a rotatable turbine. Typically, the turbine includes a closed circular, usually convex upper end which prevents ingress of rain into the sleeve and thus into the roof chamber. The turbine typically also includes a lower ring and a series of arcuate turbine blades extending from the lower ring to the upper end through which hot air flows. The turbine blades are rotatable due to wind or breezes or to the flow of air from out under the roof through the turbine.
Static roof ventilators, also commonly referred to as “pot vents”, are also used extensively to increase ventilation. Conventional static ventilators typically include a flange or base portion, a conduit or duct portion and a hood or cover portion. The flange is typically secured to the roof deck over a similarly sized aperture as with the conduit portion.
Although somewhat useful, some of the prior art ventilators suffer from numerous drawbacks. For example, some prior art ventilators are considered as presenting poor visual aesthetic characteristics and, hence, are generally considered detrimental to the overall aesthetical aspect of buildings. Also, some prior art ventilators being subjected to harsh environmental factors such as rain, snow, wind and the like tend to deteriorate over time. Furthermore, some prior art ventilators are relatively costly to manufacture and tedious to assemble and install.
In addition, static roof ventilators typically define a relatively large empty space. Therefore, a relatively large volume is occupied by these ventilators when they are transported, which raises shipping costs. Furthermore, roof ventilators are typically subjected to relatively strong winds and need to be therefore relatively strong and have therefore been built out of metal. This metallic construction is relatively expensive and relatively time-consuming to manufacture. Also, the use of metals often results in relatively heavy ventilators, which are therefore relatively hard to handle during shipment and installation.
Accordingly, there exists a need in the industry for an improved static roof ventilator.